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Abstract

The metal uptake characteristics of anaerobic sludge were investigated using samples collected from fullscale wastewater treatment plants. a batch acidimetric-alkalimetric titration method was used to determine the sludge surface site density and acidity constant. Results indicated that for all sludge samples studied, the surface site density (Γm) was approximately (1.5 ± 0.3) × 103 mol/g suspended solids, and the acidity constant (pKH) was approximately 6.6 ± 0.1. a batch method was used to investigate the uptake of selected heavy metals, namely, Cd(II), Co(II), Cu(II), Ni(II), Pb(II), and Zn(II) by these anaerobic sludges under different pH conditions. Results showed that the pH plays a very important role in metal uptake. the uptake of all these metals increased with the increase of pH. under field pH conditions, almost all heavy metals were in the solid phase. the metal adsorption constants were determined by fitting the experimental data using a metal partitioning model. For Cd(II), Co(II), Cu(II), Ni(II), Pb(II), and Zn(II), the normalized adsorption constants (logKS) were, 4.5 ± 0.1, 3.5 ± 0.1, 7.1 ± 0.4, 3.9 ± 0.7, 6.4 ± 0.3, and 5.9 ± 0.5, respectively. These constants could be useful in estimating the metal partitioning in a broad pH range.